156 PRACTICAL ORGANIC CHEMISTRY
double-filter. The clear filtrate is concentrated on the water-
bath until crystallisation commences and allowed to cool.
The crystals of the hydrochloride of phenylenecliamine sepai'ate
and are filtered, A further quantity may be obtained by con-
centrating the mother-liquors. Yield 6*5 grams,
Reaction. — Dissolve a few crystals in water, acidify with
dilute hydrochloric acid, and add a drop of sodium nitrite solu-
tion. A deep brown solution (Bismarck brown) is obtained.
See Appendix, p. 279,
; PREPARATION 59,
Poirrier, Chappat,./a/jm&, 1866, p. 903,
20 grms. aniline hydrochloride,
15 „ aniline.
22 „ methyl alcohol.
The aniline hydrochloride is prepared by gradually ad.cling"
cone, hydrochloric acid to aniline (20 grams in a beaker)
until a drop brought on to a piece of filter paper, stained with
: methyl violet, turns it green. The liquid is quickly cooled and
stirred so as to produce small crystals. It is then filtered, well
; pressed and dried on a porous plate. The dry hydrochloride is
' , brought into a thick-walled tube closed at one end, and the
mixture of aniline and methyl alcohol added. The tube is then
; sealed in the ordinary way and heated in the tube furnace
i gradually to 150° during two hours, and then to 180—200° for
j six hours more. The contents of the tube divide into two
I layers, the lower one consisting of the hydrochloride of the
J base and water, and the upper one of the free bases. The whole
j of the contents are poured out into a large separating funnel,
;| and caustic soda added in excess. The addition of a little ether
II causes the bases to separate out more readily. The top layei*
f! I is removed, and the lower aqueous portion is shaken up twice: